Abstract
A total number of 16 sexual mature bucks and 190 monoparous do of New Zealand White (NZW) rabbits were used in two experiments. The first experiment aimed to evaluate some reproductive traits of NZW rabbit bucks by conventional techniques. Semen was collected using an artificial vagina and evaluated for semen volume (ml); Individual advanced-sperm motility (%); sperm-cell concentration (x106 sperm/ ml); the percentages of dead spermatozoa; total-sperm abnormalities and acrosomal damages. Evaluated pooled semen samples were divided into two homogeneous parts then diluted 1: 5 (45.4x106/ 0.5ml) and 1:10 (22.52x106/ 0.5ml) with glucose yolk citrate diluent. While the second one was designed to measure the length of the ten slaughtered NZW rabbit doses vaginal tracts. In case of fertility traits, 180 monoparous rabbit does were divided into six comparable experimental groups (30 each) and were inseminated artificially. The pipettes of insemination were guided carefully into vaginal tract to depth of 4, 8 or 12 cm with two dilution rates (1:5 and 1:10) to give finally 6 experimental groups. The conception, kindling rate and litter size at birth were recorded.
The obtained results revealed that 1:5 dilution rates showed the highest significant (P≤0.01) physical semen characteristics compared to 1:10 dilution rate. Results of second experiment were reported that: the average length of the vaginal tract in 10 females was 14.5 to 19.5 cm.
Generally, semen dilution rate at 1:5 (33.520x106 motile spermatozoa/ 0.5 ml diluted semen); resulted high significant (P<0.05) conception and kindling rates. These results were significantly (P<0.05) superior than results of semen at dilution rate 1:10 (16.760x106 motile spermatozoa/ 0.5 ml diluted semen). Similarly, the conception rate was increased significantly (P<0.05), where the insemination catheter deeply deposits diluted semen into vaginal tract to depth 12 cm, giving better conception and kindling rates than in the case of 4 or 8 cm while litter size at birth was non-significant in both different concentration and insemination site.
It could be concluded that, rabbit does inseminated artificially are affected by sperm cell concentration and site of insemination. Increasing in number of spermatozoa (45.04×106/ 0.5 ml) in dilution rate 1:5 and deposit inter vagina at 12 cm improved conception and kindling rates while litter size was not affected.

Key words: Rabbit, semen, dilution rate, AI, straw length, vaginal tract